Credit: ESA/Hubble & NASA
This NASA/ESA Hubble Space Telescope image shows an edge-on view of the spiral galaxy NGC 5023.
Due to its orientation we cannot appreciate its spiral arms, but we can
admire the elegant profile of its disc. The galaxy lies over 30 million
light-years away from us.
NGC 5023 is part of the M51 group of galaxies. The brightest galaxy in this group is Messier 51, the Whirlpool Galaxy,
which has been captured by Hubble many times. NGC 5023 is less fond of
the limelight and seems rather unsociable in comparison — it is
relatively isolated from the other galaxies in the group.
Astronomers are particularly interested in the vertical
structure of discs like these. By analysing the structure above and
below the central plane of the galaxy they can make progress in
understanding galaxy evolution. Astronomers are able to analyse the
distribution of different types of stars within the galaxy and their
properties, in particular how well evolved they are on the Hertzsprung–Russell Diagram — a scatter graph of stars that shows their evolution.
NGC 5023 is one of six edge-on spiral galaxies observed as part of a study using Hubble’s Advanced Camera for Surveys.
They study this vertical distribution and find a trend which suggests
that heating of the disc plays an important role in producing the stars
seen away from the plane of the galaxy.
In fact, NGC 5023 is pretty popular when it comes to astronomers,
despite its unsociable behaviour. The galaxy is also one of 14 disc
galaxies that are part of the GHOSTS survey
— a survey which uses Hubble data to study galaxy halos, outer discs
and star clusters. It is the largest study to date of star populations
in the outskirts of disc galaxies.
The incredible sharp sight of Hubble has allowed scientist to
count more than 30 000 individual bright stars in this image. This is
only a small fraction of the several billion stars that this galaxy
contains, but the others are too faint to detect individually even with
Hubble.
Source: ESA/Hubble - Space Telescope
